1. Field of the Invention
The present invention relates to a DC-DC converter control circuit capable of achieving an enhanced driving efficiency while securing circuit stability during light-load driving of the DC-DC converter through variation of an on/off duty ratio of a burst mode according to load, and an image display device using the DC-DC converter control circuit and a driving method thereof.
2. Discussion of the Related Art
Generally, a DC-DC converter functions to output a specific constant voltage upon receiving a constant voltage input. Such a DC-DC converter has characteristics in that the driving efficiency thereof is varied in accordance with load conditions of an output stage.
That is, the driving efficiency of the DC-DC converter is increased under high-power heavy-load driving conditions, whereas the driving efficiency is decreased under light-load driving conditions. Such characteristics are exhibited due to voltage loss generated during switching operations of switches. In particular, under light-load driving conditions, the DC-DC converter is greatly influenced by switching voltage loss, so that driving efficiency is further decreased.
In order to solve the above-mentioned problem, in conventional cases, an error amplifier is used. That is, the error amplifier detects the load at the output stage of the DC-DC converter. When the detected load is light load equal to or less than reference load, a burst mode is carried out to turn off the DC-DC converter.
In the conventional load detection system using the error amplifier, however, the on/off reference of the DC-DC converter is varied in accordance with the load at the output stage of the DC-DC converter. Furthermore, variation of the on/off reference is great. For this reason, it is impossible to easily control the on/off timing of the DC-DC converter.
Also, when the DC-DC converter is turned on or off in a burst mode, the driving efficiency thereof is varied in accordance with variation in load at the output stage of the DC-DC converter and an output frequency band of the DC-DC converter. In the conventional system for driving the DC-DC converter in the burst mode, however, it is impossible to control the on/off duty ratio meeting the load or frequency band at the output stage. For this reason, system efficiency is low.